Apparatus for forming propeller blades



July 14, 1936. J. SQUIRES APPARATUS FOR FORMING PROPELLER BLADES FiledJuly 5, 1-933 4 Sheets-Sheet 1 ATTORNEYS.

m T N E V m July 14, 1936. J, E 2,047,296

APPARATUS FOR FORMING PROPELLER BLADES Filed July 5,, 1955 4Sheets-$heet 3 I E z 4 1 m a 6 a .z o a z w .ZE z 9 4 i 6 y Jl k \\\k lw m w a 7 5 3 6 4 4 2 7 2 5. a w w, 33 3 5.0:? 4 him. f 4 I I M a w a MJ W J a .z ,r a. a L a .h 5 w W 4 23. 0 .Z M l m w f \lk W m f m 5 A 1 w5 July 14, 1936. J. SQUIRES 2,047,296

APPARATUS\FO R FORMING PROPELLER BLADES Filed July 5, 1933 4Sheets-Sheet 4 mo W W Pier-55 INVENTOR 6Q a; re s.

- I BY Y :I'ORNEYS. I

1931, Serial No. 530,541..

, Patented Jul 14, 1936 umrsli STATES PATENT OFFICE.

2,041,296 arrannrusron roams rnornnrna BLADE k .lohn Squires,Hagerstown, Md. Application July 5, 1933, Serial No. 679,134

42 Claims.

' Objects of the invention relate to an improved apparatus for provedapparatus in. which a heated blade blank may be quickly positioned forreceiving a pressin; operation, immediately upon removal from aiurnace,and before the temperature of the blade decreases materially; to providemeans in apparatus of this kind for supporting a propeller blade blankby engagement only with its rootend-portion which is not deformed in thepress ing operation was to obviatethe cooling efiect which wouldotherwise be caused by contacting of the remalningparts of theblank'which are .to be deformed, with the dies and their support-' ingstructures; to prevent unintended deformation in restricted .areas ofthe shed product by a precooling of limited areas of the blank; to

provide a'yieldably mounted supporting structure for holding a heatedpropeller blade blank between, and in spaced relation'to a pair offorming dies which is adapted'to guide the movement or the blade, as thedies are brought to- .gether, so as to properly place the blade in the.die depression; to provide a yieldably mounted support of this kindwhich is movable axially oi the die depression for permittinginwardmovement of the root end of the blade during shrinking thereofupon cooling after it is pressed 1 to the desired blade shape; and toprovide a. detiachable holding member in a supporting strum ture of thischaracterior receiving the flanged root end portion of the blank; whichis adapted to be removed and replaced so as to condition the supportingstructure for receiving blanks oi difierent sizes and shapes.

Other objects include the provision or a die structure of novelconformation for pressing a propeller blade blank to blade shape; toprovide such a die structure a portion of which may be employed inpressing bla to blade shape regardless of the, length 01 the blade; toprovide such die structure in which the end portion thereof employed forpressing portions of the blade are readily removable and replaceable bycorresponding portions adapted for use in formlng blades of differentcharacteristics; and to provide dies and apparatus for forming propellerblades which are fabricated from two or more forming propeller blades;to imchange between a heated blade tinuously controlled duringproduction of such structures during the repetitions of the compressingoperations. which occur within short time intervals in manufacturingpropeller blades on a production basis; to provide improved means formounting the dies in the die holders y means of, which dies of variousdimensions may be secured in place; and to provide means and apparatuswhereby the rate of heat interblank and the forming dies therefor may beaccurately and conblades so as to effect the desired physical structurein the finished blade. Other objects are to provide improved mechanismin propeller blade forming apparatus for forming a communicativeconnection between the interior of a tubular propeller blade blank and asource of pneumatic pressure so as to internally support the blankagainst collapsing during the compressing \operation; to providemechanism of this character which is adapted to quickly form ahermetically sealed connection to the open end of a heated propellerblade blank before a substantial reduction in the temperature of the-blade occurs; to provide a sealing member for the open end of thetubular blank which has a greater area exposed to the source of pressurethan that which is exposed to the internal pressure of the blank so asto create a, substantial pressure diderential on the outside of thesealing member so as to tend to firmly hold the latter in a hermeticallysealed condition against the open end of the blank by pneumaticpressure; to provide sealing means of this kind in which the pressurediderential is augmented by reductions in pressure in the interior ofthe blank such as are caused by leakage or air from the open endthereof. 0 A Other objects of the invention are to provide ayieldablymounted supporting structure for receiving the flanged end of apropeller blade blank in which a passage is formed for' conducting acooling medium around the flanged end portion of the blade; and toprovide asupporting structure of this kind which may. be 'used inconjunction with die holding members having cooling medium passages soas to cool the entire converted by the addition blade uniformly and withpneumatic pressure applying apparatus during a quenching operation inwhich the outer faces of the blade are pneumatically urged againstcorresponding surfaces of the die.

Other objects include the provision .of dies for pressing a propellerblade blank to blade formation in which certain portions of the die de--pressions are of greater dimensions than the corresponding portions ofthe blades to be formed thereby; and to provide such dies in which thatportion of the die depressions adapted to form the tip end of the bladeare of greater lateral and longitudinal dimensions than thecorresponding portions of the blade to be formed thereby.

The above being among the objects of the present invention, the sameconsists of certain novel features of construction and combinations ofparts to be hereinafter described with reference to the accompanyingdrawings, and then claimed, having the above and other objects in view.

In the accompanying drawings which illustrate a suitable embodiment. ofthe present invention and in .which like numerals refer to like partsthroughout the several different views,

Figure 1 is a side elevationalview of a hollow metallic blank adapted toform a. propeller blade when properly acted upon by suitable apparatus.

Fig. 2 is a transverse secti nal view taken on the line 2 2 of Fig. 1.

Fig. 3 is a side elevational view of a pro eller blade which has beenformed from a bla of the character disclosed in Figs. 1 and 2.

Fig. 4 is a transverse sectional view taken on the line 4-4 of Fig? 3.

Fig. 5 is a fragmentary perspective view of an improved formingapparatus preferably employed for pressing the blank indicated in Fig. 1to blade shape, showing parts thereof removed to disclose. theunderlying structure. i I

Fig. 6 is a horizontal sectional view taken centrally through theforming apparatus as on the line 6 6'of Fig. 7, showing the dies thereofin closed position and illustrating the mannerin which'the blank ismounted and internally supported.

Fig. '7 is a vertical sectional view taken on the line 1-1 of Fig. 6.

Fig. 8 is a fragmentary partially broken top plan view of the apparatusillustrated in Fig. 6,

a portion of the upper wall having been removed to disclose the coolingmedium passages therein. Fig. 9 is a'front end view of the formingapparatus showing the die holders and, diesein their adjacent closedposition.

Fig. 10 is a transverse vertical sectional view taken on the line l0--ifl of Fig. 6.

' Fig. 11 is a. front end view, similar to Fig. 9, but showing the dieholders and dies spread apart and the blank supported between the diesin spaced relation to both thereof. I

Fig. 12 is a fragmentary vertical sectional view taken on the'line l2'l2of Fig. 8. t

Fig. 13 is a fragmentary perspective view of a quenching apparatus intowhich the forming,

apparatus above disclosed may be conveniently of. accessory equipmentand showing a further development of this phase of my invention.-

Fig. 14 i's"a ,front end elevation of the structure in Fig. 13

Fig. 15 is a fragmentary longitudinal sectional view taken verticallythrough the center of the,

. ticularly in the larger structureshowii in Figs.'13 and 14, as on theline lS-IS of Fig. 14.

Figs. 16, 17, and 18 are views corresponding to a fragment of the viewsshown in Figs. 6, 7, and 10 respectively, showing a variation in theformation of the die depressions from that shown in the previousfigures.

Referring to the drawings, in Fig. 3 is shown a propeller blade of thehollow metallic type including a main body I00 having a t p I02 on oneend thereof and a radial flange I 0 at the other end thereof, the flange16 serving as a means for securing the blade in a hub (not shown). Thebody l00.of the blade for the greater part of its length is of courseformed to an airfoil section such as indicated in Fig.i4 to provide aleading edge I08, a trailing edge H0, a front or camber face. 0a andrear or flat face Ilflb. It is of course also understood that the body I00 of the blade is twisted or warped over its length so that eachincrement of length has substantially the same pitch with respect to theaxis of rotation of the propeller of which it is to form a part. Inaccordance with the present invention, the blade shown in Fig. '3 isformed from a blank of ethe general type indicated in Fig. 1, namely, ahollow metallic blank 2, which may be formed from any suitable metal butwhich, for the purpose of illustration only, may be considered as formedfrom a suitable low carbon steel and preferably of a type similar to thetypes known as S. A. E. 4130,X and S. A. Ee6135. As indicated in Fig. 2,the blank H2 is preferably of circular section and one end thereof istapered down or reduced in diameter to form a small closed end or nosesection I34 and the flange [08 is preferably formed at the opposite endprior to its being pressed to the blade formation indicated in Fig.3.The wall thickness of the blank preferably decreases. from the flangeI06 toward the small closed end or tip but as pointed out in theapplication of which the present application is a continuation in part,the extreme tip end of the blank 2- -is preferably, particularly in thelarger sizeseprovided with a tip end wall of increased thickness ascoinpared to the adjacent portions of the blank. Also it is preferable,parsizes of blades, to provide a small nipple I H on the extreme pointof the closed end of the blank to prevent splitting of of this method isgiven at'this point. It will be understood that the die structureincludes two main parts relatively movable toward and away from eachother, the adjacent faces of theparts having opposed depressions thereinwhich coopera'te, when the dies are in closed position, to form a recessof the exact shape and contour and, preferably, except, for the "outerstages of .the blade, as will be explained in greater detail, the exactsize or the desired finished blade. In this connection it may be notedthat in the broader aspects of the present invention the die depressionsmay cooperate to form a depression conforming exactly throughout to theexact size, shape and contour of the desired finished blade ashereinafter shown and described, but a more limited phase of my'invention deals with making the outer or tip stages of the depressionswiderand.

longer than the corresponding portions of the between the die pits andits interior is placed under a suitable air pressure, and the dies arethen brought together, causing the exterior of the blank to assume theshape of the walls of the die depressions. The purpose of placing theinterior of the blank under air pressure is to cause it to beexpansively pressed outwardly into contact with the walls of the diedepressions during the pressing operation, thereby insuringsubstantially complete contact between the blank and the walls of thedepressions over the entire outer surface of the blank. The air pressureemployed for this 7 purpose, while high enough to insure theeflectiveness of its purpose is, of course, not sufll'ciently high toendanger bursting of the walls 01' the [;blank. 'It has been found thatan air pressure of three hundred pounds per squareinch is usually amplefor the purpose described, but this pressure may vary in accordance'withthe size and wall thickness of the particular blank being worked upon.In applying such air pressure to the interior of the blank it is, ofcourse, necessary for optimum results that such pressure be exerted atthe desired mardmum value substantially immediately upon admitting theair to the blank and be maintained at such value during theoperation.For this reason it is preferableto employ an air reservoir tank (notshown) in connection with the air supply and maintain the pressure in itat a suijficiently high figure to insure an ample sup- "ply of air forthe operation at the desired value.

In any caseit will be apparent in connection with this phaseof operationthat the temperature of the blank and the pressure of the air to whichthe interior of the blank is subjected have, of

course, a certain relation between them, the temperature necessarilybeing such as to permit the necessary bending of the walls of the blankinto blade formation without causing any undesirable stress or fractureof the metal of the walls and, of course, sumciently high to insure theinternal "pressur of the air forping the blank into 'substantial contactwith all surfaces of the die depressions when the dies are broughttogether, but preterably a temperature not so high as to pert theexpansive force of the air to stretch the metal or the blank. [a

In placing the heated blank between the dies, it is further desirable tomaintain the main body portion of the blank out of contact with the diesuntil the dies are actually brought together, for otherwise any area ofthe blank which contacted with the dies might be cooled to such anextent that whe the dies were brought together that area woul ave becomeso rigid as not to properly conform to the shape of the correspondingdepression wall area of the dies. Unequal cooling might also set upundesirable unequal stresses in the metal at various points in theblank. In view of the fact that the shank or root end portion of .theblank is not deformed during the pressing operation, this portion of theblank is preferably employed for supporting the blank in thedies beforethe dies are brought together as it thus makes little difference whetherit is pro-cooled or not.

Where the dies are employed for successively forming a large number ofhighly heated blanks to ,bladeshape, by repeated contact with successivehcatedblanks the die parts in some cases are liable to be heated to sucha degree as to become detrimental, and for this reason it may bepreferable to-provide suitable means for regulating the temperature ofthe die parts. This may conveniently be accomplished by circulating acon trolled supply of water through the die parts.

v Furthermore, in view of the fact that a preferred later step in themanufacture of the blades is a quenching operation to harden the blademate- 10 rial, and a preferred method of quenching the blades is toplace them between relatively cold die parts contacting substantiallythe entire outer surface of the blades, the same die parts as areemployed for forming the blanks to blade shape 15 may be employed inquantity production for the quenching operation if suitable means arepro-. vided for cooling the die parts. The water passages reierred toabove offer a suitable means for 1 accomplishing the desired cooling ofthe die parts. 2.0v

In the form shown-in Figs. 5 to 12, inclusive, my 1 improved propellerblade forming apparatus includes a. lower block or die holder 250 whichnor- ,mally rests upon the lower platen of a press, and

is provided with a longitudinal recess 252 which 25 is bounded by avertical side wall 256 and an inclined side wall 256. As indicated inFig. 7, the die holder 250, is cored internally or otherwise vsuitablyprovided with passages 258 for circulating a cooling mediumsubstantially throughout 30.

' its entire length andbreadth. As best indicated in Fig, 10, thepassages 25B are provided with a communicating inlet 26d, and acommunicating outlet 262 which, in practice, are connected to aconvenient source of water supply and drain pipe 35.

respectively. g

Formed on the frontpcorner portions of the lower die holder 250 areupright posts 26d of substantially rectangular, cross-section. An upperdie holder 2% having a recess 2th which is com- 549 plementary to therecess tfiliof the lower die holder 25B is mounted in superimposedrelation thereon. The opposite front corner portions of the/upper dieholder 2% are provided with recesses till for slidably receiving theposts tilt of v the lower die holder tilt. The side walll'll of therecess 2th is vertical and is located substantially in alignment withthe side wall rat of the lower recess 2%, and'the other side wall tiltof the recess 268 is inclined oppositely with respect 50 to the sidewall 2% of the other recess.

Seated in the recesses 252 and 26d of the die holders 2% and 2% are diestilt and till respectively having longitudinally extending blade formingrecesses M8 and M9 respectively formed .55 intheir'opposed faces whichrecesses cooperate to form a single recess which conforms in size,shape, contour and pitch truth the size,shape and contour, except forthe nose end as will hereinafter be more fully explained, and pitch ofthe so finished blade shown in Fig. 3 which it is desired to form. Thedie parts lit and till are preferably split transversely of their lengthand intermediate their ends as at 281i and are detachably v secured totheir respective die holders by longi- 5 tudinally extending gibs orwedge members 28d and 285 (see Fig. 10) which are held in place by bolts288 and 290 respectively screwed into the die holders 250 and 266respectively. The dies are held against outward or lateral displacement7 from the recesses by the inclined walls thereof and by the inclinedsides of the gibs 284 and 286.

By replacing those portions of the dies 216 and 211 inwardly of the lineof split by portions of either greater or lesser length than thoseshown,

the same outer die portions may be employed to produce blades ofdifferent lengths. By this means a considerable saving in die costs maybe realized in the production of bladesof different lengths. It may bedesired to employ various butt end die sections withvarying tip end diesections and the construction described makes them easilyinterchangeable to produce any desired combination, without thenecessity of making complete dies of all the various types needed.

It will also be noted from an inspection of Figs. 6, Land 10 that thedepressions 218 and 218 in the dies 216 and 211 are wider and longerthan the corresponding portion or the blade in the outer stages thereof.This may exist for as much as sixty percent of the length of the bladetoward the tip end. This is arranged by extending those surfaces of thedie depressions 218 and 219 which give such portion of the blade itsdesired surface conformation in length, out to near the parting line ofthe dies, and extending the corresponding surfaces of the dies laterallyto near the parting line in a tangential direction with respect to thenatural radius of the respective edge portions of the blades formedtherein. This permits the making ofblades of various lengths with thepitch twist continuing uniformly together with the proper longitudinaland lateral conformation.

It is to be understood that except for'the outer portions of thedepressions 218 and 218 which may be made wider and longer than thecorresponding portions of the blades to be produced thereby, as abovepointed out, the perimetrical dimensions of the die depressions at anygiven transverse cross section through them is substantially equal tothe peri'inetrical dimensions of the corresponding section of the blank2 to be shaped between them, so that when the blank is pressed to bladeshape, no outward stretching or inward crowding of the metal of theblank occurs, such metal being merely bent to shape.

The upper die holder 266 is internally cored or otherwise suitablyprovided with cooling medium passages 292 which communicate with asupply pipe 284 and a drain pipe 296 at the opposite sides of theholder.

A pair of parallel plates 298 are located adjacent the outer sides ofthe upright posts 2640f the lower die holder and are rigidly securedthereto by bolts 388. The plates 288 protrude beyond the forward ends ofthe die holders and they are provided at their outer extremities withwardly extending cleats 382 which are secured in place by bolts 384. Thecleats 382 formchannel ways 386 between their inner sides and the frontedges of the posts 264 in which side flanges 388 and EH8 of a channelshaped support or cross head 3E2 having a weby3l4, are slidablyreceived. As best shown in Figs. 6 and 12, the inner edge portions ofthe flanges 388 and 3l8 are provided with recesses 316 in which shoes3l8 preferably comprising rectangular metal bars, are seated. The shoes3l8 carry pins 328 which are received in apertures 322 formed in theposts 264 of the lower die holder 258 and the shoes are yieldably heldin spaced relation to the posts 264 by springs 324 which surround thepins 328 and are seated in recesses 326 in the forward edges of theposts and surrounding the apertures 322. These shoes 3l8 normally bearupon the cross head 3l2 urging the same outwardly against the innersides of the cleats 382.

As best shown in Fig. 11, the entire cross head 3i2 is yieldablysupported on coil springs 328 'lows 346, but this may not be essential.The

which are seated upon the lower press platen 338. The springs 328normally hold the cross head M2, and the blank 2 when supported thereby,more or less centered between the dies and out of contact with bothdies, as indicated in Fig. 11.

The web 3 of the cross head 2 is provided with an enlarged centralopening 338 of circular contour in which a collar- 332, for receivingthe shank portion of the tubular blank 2 adjacent 10 the flange I86thereof, is detachably mounted by screws 334. The collar 332 is providedwith preferably horizontally andlaterally extending slots 336 which mayregister with the flattened portions toward the leading and trailingedges which are formed on the resulting blade and permit the blade to bewithdrawn from and through the collar during removal of the blade fromthe forging apparatus, The forming apparatus may be readily conditionedfor manufacturing blades of various dimensions by removing the collar332 and replacing it with a collar of suitable inner diameter and "bysubstituting proper dies or die sections for the dies 216 and 211 shown.The cross head 3l2 serves as the sole support for the propeller bladeblank 2 before the dies are brought together and by reason of theelevated position in which it is held by the springs 328, it locates thetubular blank 2 in spaced relation between the dies 216 and 211 whenthey are spread apart and in registration with their recesses 218 and218 and holds the blank out of contact with the dies and theirsupporting structures so as to prevent cooling of localized areas of theblank before compression thereof to blade shape.

In supporting the blank internally by pneumatic or other fluid pressureafter it is positioned in the collar 332, it is necessary to form acommunicative connection between the open end of the blank and a sourceof pressure in a brief time interval in order to prevent excessivecooling of .the blank before the forming operation. This is successfullyaccomplished by providing the connecting means on a. breach block 338which is swingably mounted on a vertical breach block pin 348 that ismounted in brackets 342 on the flange 3| 8 of the cross head 3 l 2. Arelatively positive seating of thegair inlet 356 on the flange I86should be provided:\= '1'his may be accomplished by a suitable washer orother contacting member, or the contacting member maybe somewhatresilient. Such a resilient seating device is illustrated as provided bythe sylphon or belinner side of the breach block 338 has a recess 344 inwhich'the outer end of a metallic bellows or sylphon 346 is suitablysecured in sealed relation therewith. Mounted on the inner end of thebellows or Sylphon 348 is a head 348 haying a central protruding bosswhich is received in the open end of the tubularvblank H2. A washer orgasket 358, preferably comprising copper or other suitable material, isprovided between the flange I86 of the root end of the tubular blank 5and the face of the head 348 for forming an air tight seal between thehead of the bellows and the flange of the blank.

Leading to the interior of the bellows 346 and formed in the breachblock 338 is an aperture 352 in which a nipple of an outwardly extendingvvalve 354 is mounted. The valve 354 communicates through a flexibleconnection with a source of pressure (not shown) and when open suppliesair or other gas under pressure to the interior 76 is releasably held ina of the bellows 346 and from the latter to the interior of the tubularblank through an orifice 356 in the head 3480f the bellows. The side ofthe head 348within the bellows 346 is larger in area than the end of thebase which extends into the open extremity of the blank and therefore aforce differential is created by the pressure on the opposite sides ofthe head 348 which presses the gasket 350 uponthe flange I06 of theblank with a pressure of large magnitude, thus forming an effective sealat the open end of the blank. Any leakage which may occur from theinterior of the blank tends to increase this force differential andaccordingly increases the pressure upon the extremity of the blankpreventing continued leakage. sure of 300 pounds per square inch in theblank, a load of 6,000 pounds may be exerted on the flange by suitablyproportioning the parts referred'to, thus tending to insure sufficientpressure with-in the blank to cause it to hug the dies when they areclosed. 7

'As best shown in Figs.- 5 and 6, the breach block closed position by alatch device which includes a vertical cylindrical bar 358 journaled inbearings 360 mounted on the flange 308 of the cross head 3I2. This bardsprovided with an axially extending V-shaped groove in its surface and itis provided with an outwardly extending radial pin 362 by which it maybe rotated to bring the V-shaped groove into registration with aprotruding edge or lip portion 364 on the free side of the breach block.Adjacent the projecting lip 364 of the breach block is a recess 366 inwhich the cylindrical portion of the bar 358 is received when the latteris held in locking position by the spring 368 engaging the pin 362. Thebreach block may be unlocked and swung to open position, shown in dottedlines in Fig. 6, by moving the pin 362 against the tension of the spring368 and so rotating the bar 358 in a counterclockwise direction to allowthe projecting lip 364 on the breach block to pass by the groove in thebar 358.

In operation, either. the upper or lower die holders may be moved so asto bring the dies together, but the lower die holder 250 is preferablylifted vertically upward with substantial force by mechanism (not shown)of the character customarily used in die forming operations. Atubular,blank I I2 of the type shown in Fig. 1, having a flange I06 onits open end is heated to a workable temperature in any suitable mannerand is lifted, preferably by tongs inserted in the, open end of theblank, and inserted through the cen-' tral opening in the replaceablecollar 332 while the cross head 3I2, lower die holder 250 and upper dieholder 266 are in the relative positions shown in Fig. 11, and while thebreach block 338 is open. In order to obtain uniformity of final productand insure optimum conditions of balance in the finished product, theheavy side of the blank, if any, as preferably determined and marked, inprevious operations is positioned on the centerline of thedies whichform the flat face I IN) of the blade, these being the lower dies 216and 218, as shown. The blank "-2 is inserted through the central openingof the collar 332- until the flange I06 thereof engages the outer sideof the collar and then the breach block 338 is swung to a closedposition with the boss of the head 348 of the bellows 346 extending intothe open end of the blank, the gasket 350 being located between theflange I06 and the head 348.

The cross head, which is yieldably held in an ele- In practice, with thepresthough it may be vated position by the springs 328, positions theblank in registration with the recesses 218 and 219 of the dies 216 and211, and holds the blank out of contact with the dies and theirsupporting structure so as to prevent pre-cooling of localized areas ofthe blade, as previously mentioned, al-

that, at least before the breach blade being more or less loosely heldin collar 332 may sag so as to touch the die at its tip, but this maynot be harmful as the previously described thicker wall at the tip mayprevent dangerous pro-cooling during the short period of contact if any.Furthermore, as preblock is shut, the

vent the extreme tip of the blade, which is subpressure of -ing movementof the cross head in the die closing 15 jected to the greatest bendingefiects in the blade during formation, from splitting open even thoughit may become cooled to a slight extent.

Before the lower die holder 250 and die 216 are urged upwardly to formthe valve 354 is opened so as to admit air into the bellows 346 and tosupply'air to the interior of the tubular blank. The pressure in theinterior of the bellows is applied directly on the inner side of thehead348, holding the head in air sealing 25 relation against the flange I06of the blank. A

300 pounds per square inch is preferably employed where a blank of usualsize is made of the ordinary range of low carbon steels and thispressure is preferably. substantially immediately built; up in the blankso as to internally support the latter and to hold all portions of itswall in contact with the surfaces of the recesses in the dies when thelower die is urged upwardly from the position shown in Fig. 11. Thelower die, in moving upwardly, first engages the blank and rapidly movesit, together with the cross head 3I2, upwardly against the weight of theblank and the force of the springs 328 until the dies 216 and 211contactwitheach other and the blank which then assumes its desired bladeshape in the depressions 218 and 219 between them. The flanged end ofthe blank, of course, constantly maintains its engagement with the head348 duroperation. The closing. movement of the dies is so rapid that thedies contact the entire blank at as near the same timeas possible. Thisis desirable in order to avoid unequal chilling which might occur ifthere was, die contact at one point before another. This rapid andcomplete contact makes it possible to act upon the blankwhile all themetal is at a temperature to be readily shaped.

As the blank cools and shrinks its tapered end is free to "contractlongitudinally in the tapered portions of the die recesses. The otherend portion of the blank, however, is allowed to move "inwardly withrespect to the dies against the action of the springs 324 .cross head3I2, upon which the flange I06 of the which yieldably hold the blank 2bears, in spaced relation to the adjacent ends of the die holders. Inthis manner, setting up of internal strains in the propeller bladeduring cooling thereof is minimized.

The dies and die holders may be protected from overheating by repeatedcontact with successive blanks, when used continuously in such pressingoperations, by circulating a cooling medium through the passages 258 inthe lower die. holder and 282- in the upper die holder. As previouslymentioned, the provision of such cooling medium circulating passagesfurther adapts the dies and die holders for use in a preferredsubsequent quenching operation, as previously mentioned.

theblank to blade shape, 20

When the pressed blank in the dies has cooled suflicientlyto insure itsretainingits now bladelike form, which will ordinarily be after a periodof about one minute, the valve 354 is closed, the air is released fromthe interior of the blade, and the breach block 338 is swung back, andthe blank, which is nowtransformed to a blade, is

removed, the notches 336 in the collar 332 functioning to take care ofthe increase in lateral dimensions of the blade as compared tocorresponding dimensions in the blank.

Blades thus received from the dies are checked for ,length, and are thensubjected to a suitable cleaning treatment to remove all paint and scalefrom the outside of the blade. This cleaning operation may beconveniently accomplished in any suitable and convenient manner.

While the blades thus formed are, for the most part, in commerciallyacceptable form, I find it desirable in order to make a more perfectproduct, to subject them to a heat treatment. This may be suitablyaccomplished by suspending each blade byits flange l 06 in any suitablefurnace and there subjecting it to a heat soaking process for asuflicient length of time to evenly diffuse the carbides in the metalwhen carbides are present therein, or for a sufficient length of time toeffect other desirable changes in the structure of the metal. The lengthof this soaking treating, as well as the temperature at which it iscarried on will, of course, vary according to the particular metal ofwhich the blade is formed, but for low carbon steels I have found thatsoaking the blade for approximately thirty minutes at a temperature inthe neighborhood of 1625 to 1675 degrees Fahrenheit will sufiice. Thissame soaking treatment not only evenly diffuses the carbides in themetals, with other usual eifects to the structure thereof but,furthermore, relieves any strains that may have been set up in the metalin the die-pressing operation.

The blade is now removed from the furnace and may again be placed whileat high heat within the same dies just described, or equivalent dies,which are closed, andthe blade is then subjected internally to airpressure as previously described. Air pressure in the neighborhood of300 pounds per square inch is found to be satisfactory, althoughpressure of either above or below this figure, preferably above; may beemployed as well. As before, a complete and rapid closure of the dies isdesirable to produce the best result. This treatment not only forces outany small depressions or irregularities in the surface of the blade thatmay have failed to disappear in the original pressing operation, and notonly'will straighten the blade if the same has become warped at all inthe soaking treatment due to the relieving of.

but, more important, the

the strains in the metal air under pressure may force all portions ofthe blade surface into contact with the surfaces of the depressions ofthe dies, and in doing so causes a chilling of the metal of the bladeand prevents separation and segregation of the carbides in the metalthereof, or other undesirable changes in the structure of the metal. Atthe same time that the main body portion of the blade is being chilledin the dies, a spray of water may be directed onthe flange I 06 thereofto cause a like effect. A period of two minutes in the closed dies willusually be found ample to effect the desired chilling of the blade.While this operation of putting the exterior walls of the blade intocontact with the relatively cold walls of the dies is a chillingoperation on the blade, I prefer to call it a die-quenching operation;since the results are in all ways analagous to immersing hot steel in acooling liquid.

This die-quenching effect on the blade serves the same purpose asconventional quenching treatments, and, may be intensified, modifiedand/or-controlled in several ways, one of which is by the provision ofwater passages such as 258 and 292 in the die supports 250 and 256 eachprovided with suitable inlets 260 and 294 respectively, and suitableoutlets 262 and 296 respectively. This, or an equivalent method ofcooling the dies may be found to be desirable if not essential where thetime element between the removal of one blade and the insertion of thenext is limited, but it will be recognized that in any case the mainrequirement is an adequate temperature difference between the dies andthe work to effect the proper quench, regardless of the method ofobtaining such temperature difference. It will be obvious that it ispossible to obtain any degree or rate of cooling to correspond to anydegree or type of quench in various ways such as by varying the rate ofpassage of a multiplicity of blades through the dies, by varying thetemperature of the dies themselves by either varying the rate of thecooling fluid passing through them or the temperature of such coolingfluid, and further by varying the temperature of the blank itself. Thusa quick, simple and economical method of quenching the blank isprovided.

Instead of relying solely upon a spray of water to cool the flange endof the blade during the quenching operation, as above described, it maybe desirable to so modify the die apparatus as to permit a moreaccurately controlled cooling of the flange end of the blade. This maybe conveniently accomplished by using the lower and upper die holders250 and 266, their respective dies 216 and 211 and thepalr of forwardlyextending parallel plates 298, shown in Figures 5 to 12, inclusive, inconjunction with the lower and upper cross head sections 310 and 312,respectively, shown in Figs. 13, 14, and 15. The cross head sections 310and 312 are provided with side flanges 314- and'316, respectively, whichare located between the ends of the die holders 250 and 266 and thecleats 302 mounted on the front edges of the plates 298, as previouslydescribed. The cross head sections 310 and 312 are secured againstvertical displacement from the lower and upper die holders with whichthey respectively register by dowel pins 318 mounted on the cross headsections and fitting loosely in cooperating apertures in the ends of thedie holders. The loose fitting relation of the dowel pins in theirapertures permits the sections to move axially of the die holders andthe sections are yieldably retained in spaced relation to the ends ofthe die holders by the same spring shoes 318 and springs 324, asdescribed'in connection with Figs. 5 to 12, inclusive, and whichnormally hold the forward edges of the flanges 314 and 316 of the crosshead sections against the cleats 302 on the plates 298. The weight ofthe lower cross may be sufficient to keep it from rising from the lowerdie holder and it may not be necessary to provide the dowel pin 318therefor.

Formed in the cross head sections 310 and 312 are complementary,semi-cylindrical recesses 38' and 382 in which-are seatedsemi-cylindrical tuhead section 310 a apmpoe bular ring segments :04 andare having cooling mifidium passages 388 and 390, respec vely. The ll gsegments 384 and 385 are provide with complementary seats 39? and at forreceiving the root end portion or shank of the propeller blade and theyare detachably held in place. on the cross head sections 310 9.net 312by screws $98. The ring sections 384 and 386 are provided with inletapertures 39b and outlet apertures Gilt for petting acooling medium,such as water, to be circulated through the passages tdt'and ttll.Formed'on the side flanges tit and Mt oi the v right hand side of thecross head sections tit ores.

and hit are hinge elements Md and tilt 'on which .a breach block W (seeFig. id) is swingably mounted, substantially in the manner illustratedin Fig. 6. The breach block tilt and the bellows or sylphon tit which itcarries, are substantially identical in construction to the breachbloclr tit and the bellows t lt whichhas been described in detail inconnection with Flash, '2, and h. The

bellows i communicate with an inlet pipe or nipple i1 oi a valve titwhich is provided for controg the admission of air to the interior oithe bellows and to the interior oiv a propeller initially supportedby,its shank so as to be held out oi contact with the dies as shown in Fig.ll. since the rings ttt and ttt are not supported by'-.

- the springs ttt. The hot blade may then be layed directly on the lowerdie and the diesclosed so suddenly and rapidly that uniform contact overthe entire surface of the blade me; be procured as promptly as possible.

in Figs. l6, l7, and 18 a slight modification of the previouslydescribeddie structure is shown in which the die depressions in the diesare so termed as to conform exactly in size, shape and contourthroughout with that desired in the huished blade instead of having theouter stages oi the depressions longer and wider than the blades asdescribed in connection with the previous fig- Since the only changesover the structure previously "described is solely in connection withthe dies tilt and l'lhall the parts indicated in a Figs. 16, 1'7, andit, with the exception of the dies themselves, bear theisame numerals asin Figs. 5 to 12, inclusive, and the dies themselves bear thesame'numerals except that they carry the subletter "a". Accordingly, itwill be noted that the dle depressions lids and 279s conform. exactly insize, shape and contour with the desired size,

shape and contour of the desiredblade ltd; it,- of course, beingunderstood that the perimetrical dimeirisions of the.conibineddepressions tits and 65 same stage of length before the blank is pressedHon taken in a plane perpendicular to the longitudinal axis of the bladeat any stage oi the length thereof; are substantially exactly equal tothe perimetric dimensiOn's of the blank at the toblade shape, so that noexpansion of or crowding in or the metal of the blank occurs during thepressing operation, but rather the metal oi- T theblank is simply bentinto the desired shape.

It might be noted that. in this case the nipple is l n is omitted fromthe end or the blank, although *2; l

' F x it will be apparent that this nipple may be providedii desired inthis case and the depressions 318a and 219s modified sufliciently topermit its reception.

Formal changes may be made inthe specific embodiments of the inventiondescribed without departing from the-spirit and substance of the broadinvention, the scope of which is commensurate with the appended claims.I claim:

i 1. Forming apparatus including a pair oi relatively movable dieholders, a pair of dies, one

mounted in each holder, and a support for posh,

tioning a piece of worlr in operative; relation with respect -to saiddies including a wort: holder shittable in the direction of relativelorming movement of said dieholders and including means for initialy sopositioning said worlr holder as to retain work held thereby in spacedrelation to both of and dies until commencement oi their lorminsoperation and to accommodate movent of said worlr holder and work heldthereby ill the direction of relative forming movement oi said dieholders during the forming operation of the latter.

2. Forming apparatus including an upper stationary die holder, a lowervertically movable die holder, a pairoi dies, one in each oi said dieholders, a vertically shiftable cross he located in close proximity tosaid dies and having an opening for receiving the end portion of ablanlr, and

yieldable members normally supporting said cross headin an elevatedposition sons to ret said blank in spaced relation to said dieswhen thelatter are spread apart.

- 3. Forming apparatus including a pair oi relatively movable dieholders, a pair of dies, one

mounted in each holder, a support shittable bodily laterallyandlengthwise of said dies in a direction toward one end thereof forpositioning a blank between said dies, and yieldable means normallyurging said support outwardly toward in a predetermined spaced positionfrom the adjacent ends ot said dies so as to accommodate resiliently.restrained longitudinal contraction oi said blanlr 4 upon cooling.

l. Forming apparatus including a pair oi relatively movable die holders,a ir oi dies, one

mounted in each holder, a support located at one end of said r oi diesfor positioning a blanlr therebetween, said support being shiitablelength-- wis;e oi said dies and shiltabie'in the direction of therelative movement thereof, yieldable means ior holding said support in apredetermined location with respect to the spread apart positions ofsaid dies so as to prevent contacting of said blanh therewith, and meansio'r yieldably holding said support in spaced relation to the adjacent'ends of said dies so as to permit longltual contraction of said blankupon cooling.

5.. Forming apparatus including, an upper stationary die holder, alowervertically vable die holder, a pair of dies, one in each oi saiddie holders, a cross-head sh'iitable vertically d lengthwise withrespect to said dies and die holders and havingan apertureior receivinga bio, springs yieldably supporting said. cross-head in an elevatedposition so as to retain said blank in spaced relation to both of saiddies when the latter are spread apart, and resilient shoes'bearingbetween said cross headand the adjacent ends or said. die holders foryieldably holding said cross head inspaced relation thereto so 'as toper- 'mit, lengthwise contraction of said blank upon cooling.

'6. Formin appcranis mai s; sna er tionary die holder, a lowervertically movable die holder, a pair of dies, one in each of said dieholders, a vertically shiftable cross-head located in close proximity tothe open ends of said dies and having an opening therein, a replaceableadapter detachably mounted in said opening for receiving an end of ablank and resilient members yieldably retaining said adapterintermediate the spread apart portions of said die holders so as toprevent premature contacting of said blank with said dies.

'7. Forming apparatus including an upper stationary die holder, a lowervertically movable die holder, a pair of dies, one in each of said dieholders, :2. cross-head located in close proximity to the open ends ofsaid dies and shii'table bodily and laterally and lengthwise thereof,means on said cross head for supporting a blank, and resilient meansyieldably holding said cross head in spaced relation to the open ends ofsaid dies and adapted to accommodate resiliently restrained longitudinalcontraction of said blank upon coolmg. i

\ 8. Propeller blade forming apparatus including a pair of die holders,a pair of dies, one in each die holder, a support adjacent one-end ofsaid pair of dies having an opening for receiving the open end of atubular propeller blade blank and adapted to independently support thelatter from the open end portion thereof, and a member swingably mountedon said support including means for registering with said openingforming a communicative connection between the interior of said blankand an external source of fluid pressure for internally supporting theblank during compression thereof to blade shape.

9. Propeller blade forming apparatus including a pair of die'holders, apair of dies, one in each die holder, a support adjacent one end of saidpair of dies having an opening for receiving the open end of a tubularpropeller blade blank, a breach block swingably mounted on said support,and a member carried by said breech block for forming a communicativeconnection between the interior of said blank and an external source offluid pressure for internaliy'supporting the blank during compressionthereof to blade'shape.

10. Propeller blade forming apparatus including a-pair of die holders, apair of dies, one in each die holder, a support adjacent one end of saidpair of dieshaving an opening for receiving the open end of'a tubularpropeller blade blank, a' breach block swingably mounted on saidsupport, and a yieldable member carried. by said breach block forforming a communicative connection between the interior of said blankand an external source of fluid pressure for internally supporting theblank during compression thereof to blade shape.

11. Propeller-blade forming apparatus including a pair bf die holders, apair of dies, one in each die holder, 2. support adjacent one end ofsaid pair of dies having an opening for receiving the open end of atubular propeller blade blank, a breach block swingably mounted on saidsupport, and a sylphon carried by saidlbreach block for forming acommunicative connection between the interior of said blank and anexternal source- 01' fluid pressure for internally supporting the blankduring compression thereof to blade shape.

12. Propeller blade forming apparatus including a pair of relativelymovable die holders, a

- pair of dies, one in each of said holders, 9. shiftable supportlocated at one end of said pair of dies for positioning a tubularpropeller blade blank therebetween, means for'yieldably holding saidsupport in a predetermined position relative to said dies so as toretain said blank out of contact with said dies when the latter arespaced apart, and means on "said support for forming a communicativeconnection between the interior, of said blank and an external source offluid pressure for internally supporting the blank during formingthereof to blade shape.

13. Propeller blade forming apparatus including a pair of die holders,9. pair of dies, one in each holder, spaced protruding elements on anend of one of said die holders, a cross-head shiftably mounted betweensaid elements having an opening for receiving the open end portion of atubular propeller blade blank, members yieldably holding said cross headin spaced relation to said i die holders for permitting inward movementof the open end portion of said blank during shrinking thereof uponcooling, and means on said cross head for forming a communicativeconnection,

between the interior of said blank and an external source of fluidpressure for internally supporting the blank during compression thereofto blade shape.

25 14. Propeller blade forming apparatus includ- I member carried bysaid breach block for forming a communicative connection between theinterior of said blank and an external source of fluid pressure forinternally supporting the blank during compression thereof to bladeshape.

15. Propeller blade forming apparatus including a pair of die holders, apair of dies, one in each holder, spaced protruding elements on an endof one of said die holders, 8. cross head shiftably mounted between saidelements having an opening for receiving the open end portion of atubular propeller blade blank, a breach block swingably mounted on saidcross head, means for releasably holding said breach block in a closedposition, a resilient member mounted on said breach block including ahead portion registering with the open end of said blank and having anaperture in communication with the interior thereof for supplying agaseous medium thereto, and means communicating with said resilientmember and a source of pneumatic pressure.

16. Propeller blade forming apparatus includeach holder, spacedprotruding elements on an end of one of said die holders, 8. cross headshiftably mounted between said elements having an opening for receivingthe open end portion of a ing a pair of die holders, a pair of dim, onein 60 tubular propeller blade blank, a breach block 65 swingably mountedon said cross head, means for releasably holding said breach block in aclosed position, an expansible member mounted on said breach blockincluding a head portion registering with the open end of said blank andhaving an aperture communicating with the interior thereof for supplyinga gaseous medium thereto, and means communicating with said expafisiblemember and a source of pneumatic pressure, the

side oi. saidhead adjacent said blank being smaller in area than theother side of said head so as to create a force diilerentia for holdingsaid head in a sealed relation on the pen end of said blank.

17. Forming apparatus including a pair of relatively movable dieholders, each having a cooling medium circulating passage therein, apair of dies, one in each. die holderfa support for a piece of worklocated at one end of said dies shittable bodily in the direction ofrelative movement of said die holders while supporting a piece of worktherebetween, and means normally yieldably holding said support in apredetermined position with respect to said dies so as to retain thework out of contact with the latter when said dies are spread apart. v

18. In forming apparatus, a support including a cross head having a seattherein for receiving the open end of a tubular blank, a member adaptedto be releasably secured on said support in spaced, substantiallyparallel relationship to said cross head, and a bellows mounted on saidmember including a head portion having an air passage therethrough andreceivable by the open end of said blank for forming a communicativeconnection between the interior or said blank and a source of pneumaticpressure. I

19. In forming apparatus, a support including a cross head having a seattherein for receiving the open end of a tubular blank, a breach blockswingably mounted on'said support in spaced relation to said cross head,and means carried by said breach block and communicating with a sourceof pneumatic pressure for forming a communicative connection between theinterior of said blank and said source oi pressure as said breach isswung to a closed position.

20. Apparatus for making propeller blades from a tubularblanhii'ncluding a pair of relatively movable die holders, a pair ofdies, one mounted in each die holder and each die including areplaceable section, a member shiftable laterally and longitudinallywith respect to the length of said dies for supporting a blank byattachment to its root end, and means normally yieldably urging. saidmember into outwardly spaced relation to one end of said pair 01 dies,adaptedto accommodate longitudinal contraction oi said blank uponcooling.

21. Apparatus for making a propeller blade from a tubular blankincluding a pair of die holders each having cooling medium circulatingpassages therethrough, a pair of dies one in each of said die holders, amember at one end or said dies for supporting the root end of said blankand having cooling medium passages therethrough, and means on saidsupport ior forming a communicative connection between the interior ofsaid tubular blankand an external source of fluid pressure.

22. Apparatus for making a propeller blade from a tubular blankincluding a pair of die holders, each having cooling medium circulatingpassages therethrough, a pair or dies, one in each of said die holders,a pair of cross head members each movably mounted on one end of said diemembers having complementary recesses for receiving the root end portionand flange of said blank and each having a cooling medium passagesurrounding its recess, and yieldable shoes normally holding said crosshead members in spaced relation to the adjacent ends of said dieholders.

23. Apparatus for making a propeller blade from a tubular blankincluding a pair of die holders, each having coolingmedium circulatingpassages therethrough, a pair or dies, one in each of said die holders,a pair of cross head members each extensively mounted on one end of saiddie holders having complementary recess for receiving the root endportion and flange of said blank and each having a cooling mediumpassage surrounding its recesses, yieldable shoes normally holding saidcross head members in spaced relation to the adjacent ends of said dieholders, and means mounted on said cross head sections for forming acommunicative connection between the interior of said tubular blank andan external source of fluid pressure.

24. Apparatus for forming a hollow article of irregular contour from ahollow blank including a pair of die holders, each having cooling mediumcirculating passages therethrough, a pair of dies, one in each of saiddie holders, a member at one end of said dies for, supporting the rootend of said blank and having cooling, medium passages therethrough, abreach block swingably mounted on said member, and-means carried by saidbreach block for forming a communicative connection with the open end ofsaid blank and a source oi' fluid pressure upon closing of said breachblock so as to internally support said hollow blank. g

25. Apparatus for making a propeller blade from a tubular blankincluding a pair of die holders, each having cooling medium circulatingpassages therethrough, a. pair of dies, one on each of said die holders,a pair of cross head members each movably mounted on one end of said dieholders having complementary recesses 1'01 receiving the root endportion and flange of said blank and each having a cooling mediumpassage surrounding its recess, yieldable shoes normally holding saidcross head members in spaced relation to the adjacent ends of said dieholders, a breach block swingably mounted on said cross head members,and expansible means carried by said breach block for formingacomrelation to said cross head, and means for yieldably holding saidcross head against movement toward the open ends of said diesincludingmembers compressible during longitudinal thermal contraction of ,saidblank for releasing the strain thereon.

2'7. Forming apparatus including a pair of relatively movable dieholders, a pair oi dies, one mounted in eachof said die holders, a.cross head located at an end of said dies and shiftable bodily in thedirection of relativemovement of said die holders, said cross head beingprovided said blank from one end thereof in a fixed with means forreceiving one end of a blank and supporting the latter between saiddies, and means for yleldably holding said blade receiving portion 01said cross head in misalignment with the closed positions oi. said diesto retain said blank out of contact with said dies when said die holdersare spread apart.

28. Apparatus for forming a tubular article having an open extremityincluding a support- 75 Iii ing structure, a pair of dies supportedthereon, a member on saidsupporting structure adjacent one end of saiddies including means for supporting a blank having an open extremityfrom the end portion of said blank adjacent its open extremity, a breachblock swingably mounted on said member, and an element carried by saidbreach block for forming a communicative connection between the interiorof said blank and a source of fluid pressure for urging the exterior ofsaid blank against said dies.

29. Apparatus for forming a tubular article having an open extremityincluding a supporting structure, a pair of dies supported thereon, amember on said supporting structure adjacent one end of said diesincluding means for supporting a blank having an open extremity from theend portion of said blank adjacent said extremity, a breach blockswingably mounted on said member, means for releasably holding saidbreach block in a closed position, and an expansible element carried bysaid breach block for forming a communicative connection between theinterior of said blank and an external source of fluid pressure, saidelement being adapted to expand under the influence of said fluidpressure for maintaining a tight seal between the contacting portionthereof and said blank.

30. Apparatus for forming a propeller blade from a hollow metal blankcomprising dies having die depressions which at an intermediate point intheir length correspond to the size of the corresponding part of theblade while leaving the tip end free to slide therein when contractingwhile cooling, and associated means for holding the hub end of the bladeadapted to give to allow the hub end to move in when the blade contractsduring cooling.

31. Apparatus for forming a propeller blade from a hollow metal blankcomprising dies having depressions which at an intermediate point intheir length correspond to the size of the corresponding part or theblade while leaving both the tip end and the hub end of the blade freeto slide therein when contracting while cooling.

32. Apparatus for forming a hollow article having an open extremityincluding a. supporting structure, dies supported thereon, a memberlocated at one end of said dies andshiftable toward the latter includingmeans for receiving an open extremity of a hollow blank and supportingthe latter from the end portion thereof adjacent said open extremity,means yieldably holding said member in a predetermined spaced rela tionto the adjacent end of said dies, a breach block swingably mounted onsaid member, and

means on said breach block registering with the open extremityof saidblank for forming a communicative pnnection between the interior thereofand an external source of fluid pressure.

33. Forming apparatus including a pair of die holders each having acooling medium circulating passage therein, a support for position ing ablank betweensaid dies, said support being 1 in the direction ofmovement of said die holders and located at one end of said die holdersand dies including means .for initially supporting a piece of work froman end portion thereof located externally of said dies, and yieldablemeans acting upon said support for holding the latter in a predeterminedposition with respect to said dies so as to retain the work out ofcontact with said dies when they are spread apart.

35. Means for forming a propeller blade from a hollow metallic blank ofgenerally circular section comprising a plurality of die members havingmatching depressions in the opposed faces thereof, the perimetricdimensions of a transverse section through said matching depressionsover 'a portion of the length thereof corresponding substantiallyexactly with the perimetric climansions of a corresponding section ofthe blank to be received therein, and the perimetric dimensions of atransverse section through said matching depressions over anotherportion of the length thereof being materially greater than theperimetric dimensions of a corresponding section of said blank.

36. Means for forming a propeller blade from a metallic blank comprisinga plurality of die members having matching depressions in opposed facesthereof, the size, shape and contour of a section taken through saidmatching depressions over a portion of the length thereof beingsubstantially identical to the size, shape and contour of acorresponding section taken through the desired finished blade, and thesize of a section taken through said matching depressions over anotherportion of the length thereof being substantially greamr than the sizeof a corresponding section taken through the desired finished blade.

3'7. Means for forming a propeller blade from a' metallic blankcomprising a plurality of die members having matching depressions inopposed faces thereof, the size, shape and contour of a section takenthrough said matching depressions over a portion of the length thereofbeing substantially identical to the size, shape and contour of acorresponding section taken through the desired finished blade, and thesize of a section taken through said matching depressions over anotherportion .of the length thereof being substantially greater than the sizeof a corresponding section taken through the desired flnished blade, butof substantially the same thickness as the last mentioned section.

38. Apparatus for pressing a hollow metallic blank to propeller bladeshape comprising a pluralityof die parts having matching depressions intheir opposed faces generally conforming to the size, shape and contourof the desired finished blade, 9. section through said matchingdepressions over the root portion of said blade conforming substantiallyexactly to that desired in a corresponding section of the desiredfinished blade. and those portions of said depressions adapted to formthe tip end portion of the finished blade being wider and longer thanthe corresponding portion of the desired flnished blade.

39. Apparatus for pressing a hollow metallic blank to propeller bladeshape comprising a plurality of die parts having matching depressions intheir opposed faces generally conforming to the size, shape and contourof the desired finished blade, 8. section through said matchingdepressions over the root portion of said blade conforming substantiallyexactly to that desired in a corresponding section of the desiredfinished blade, and those portions or said depressionsadapted to formthe tip end portion of the finished blade having opposed wall portionsgenerally conforming to the desired contour of the major portion of theopposite faces of the corresponding portion 1y movable die membershaving matching depres sions therein adapted to receive said blank andthe walls of which depressions are adapted to control the crosssectional shape of the blank when pressed to blade shape thereby, eachof said members comprising at least two parts separable longitudinallyof the corresponding depression intermediate the ends of thedepressions, the size andcontour of the matching depressions in saidparts at one portion of said members contorming substantially exactly tothat desired in the corresponding portion of the finished product, andthe size of the matching depressions in said "parts at another portionof said members varying from that desired in the corresponding portionof the desired finished product. v

41. Apparatus for pressing a tubular blank to propellerblade shapeincluding a pair of relatively movable die members having matchingdepressions therein adapted to receive said blank and the walls of whichdepressions are adapted to control the cross sectional shape or theblank dies when pressed to blade shape thereby, each 01' said memberscomprising at least two parts separable longitudinally of thecorresponding depression intermediate the ends of the depressions,

the size and contour of the matching depressions 5 in an opposed pairof. said parts for the root end portion of the blade conformingsubstantially to the size and contour desired for the root end portionof the finished blade, and the size of at least a portion of thematching depressions in v another opposed pair of said parts adapted toiform the tip ,end of said blade being greater than the dimensionsdesired in the tip end of the finished blade. v

42. Means for forming a propeller blade from a hollow metallic blank ofgenerally circular section, 01 tapered formation and having the smallerend thereof closed and provided with an axially extending nipple,comprising a plurality of die members having matching depressions in'opposed faces thereof, the size. shape and contour of a section takenthrough said matching depressions. over at least a. portion of thelength thereof being substantially identical to the size, shape andcontour of a corresponding section taken through the-desired finishedblade, the length of said depressions being greater than thecorresponding length desired in the finished blade whereby to provideclearance for said nipple during pressing of said blank toblade shapebetween said JOHN SQUIRES.

